The Environmental Technology Verification (ETV) by the United States Environmental protection agency (US-EPA) conducted a thorough testing of the Colifast ALARM . Preparations of samples containing close to 1 organism per 100 mL water was acquired to test the sensitivity of the apparatus in accordance with the EU directive and recommendations from the WHO of 0 organisms/100 ml, and thus also the standards for the Colifast ALARM . Commercial cell lines were used to prepare these samples, but also filtered contents of sewage to better simulate the in situ conditions. All samples underwent chlorination for adjustment to target level, followed by dechlorination. Results gotten from the Colifast ALARM and a reference method (SM 9221B and F), were compared statistically using the Chi-square test for independence followed by the Yate’s continuity correction. No significant differences between the tests were proven in the report.
The US-EPA also compared the Colifast ALARM and Colilert-18, where the statistics showed a difference between the two methods. The growth conditions in the two systems differ slightly and might explain the difference observed by the US-EPA. The Colilert-18 medium facilitates unspecific growth of more than coliform bacteria, and the E. coli-distinguishing feature is acquired purely based on the measurement of enzyme activity. On the contrary the Colifast ALARM runs on medium that inhibits growth of non-coliforms, and while gaining selectivity this slightly harsher treatment results in a slight loss of sensitivity. The selectivity of the Colifast medium is though, similar to the traditional ISO and American standard methods and thereby no difference, on the sensitivity, is found when comparing Colifast with these methods.
About ETV: The goal of the ETV program has been to verify and inform the public of the performance of technology that can solve problems related to the public health and the environment. The ETV program collaborates with organizations conducting recognized standards and testing in order to ensure that the data generated are both reliable and defensible.
EU Validation- DEMOWATERCOLI
Colifast technology for E. coli and P. aeruginosa was tested by three independent institutes and utilities.
- Instituto Superiore di Sanitá, Roma, Italy
- Ecole Nationale de Santé Publique, Rennes, France
- Thames Water Utilities Ltd, Reading, UK
The project tested and compared Colifast methods and on-line instruments with reference methods (ISO 9308-1 and EN 12780). In this project, the Colifast Analyzer (discontinued instrument) and CALM were demonstrated in laboratory and in industrial conditions.
Testing of the Colifast E. coli medium at the “Instituto Superiore di Sanitá” showed 97% specificity and 98% sensitivity and no significant difference between the Colifast method (14 h incubation time) and ISO 9308-1 method when 208 natural water samples were tested.